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渗透汽化技术在液体分离中的研究新进展 总被引:5,自引:0,他引:5
渗透汽化是近年膜科学研究中最活跃的领域之一,在分离液体混合物,尤其是痕量、微量物质的移除,近、共沸物质的分离等方面有独特优势。简要介绍了渗透汽化技术的历史及发展过程,着重介绍了近几年渗透汽化技术在液体分离方面的研究进展。从研究结果来看,从水溶液中分离有机物研究主要集中在醇、酯的分离。在有机物脱水方面,开发出了选择性更好、渗透量更高的膜,乙醇脱水也有不少新的研究成果。特别是在有机混合物分离方面,取得了长足的进展,可以分离更多的有机物。 相似文献
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This study dealt with the separation of binary water–phenol and water–methanol mixtures and ternary water–phenol–methanol mixtures by pervaporation (PV) with polydimethylsiloxane (PDMS) membranes. The effects of the operating conditions (feed temperature, feed concentration, and feed flow rate) on the separation performance for binary mixtures were investigated. An increase in temperature or concentration increased the total permeation flux and decreased the organic separation factor. In other words, an increase in the temperature or feed organic concentration increased the water flux more significantly than the organic compound flux, which resulted in a separation factor reduction. Also, an increase in the feed flow rate increased the total flux and separation factor because the boundary layer effects diminished. The vapor–liquid equilibrium separation factor (αVLE) and pervaporation separation factor (αPV) values for the PDMS membrane were calculated, and this showed that αPV for the water–phenol mixture was greater than αVLE. This means that the membrane was highly efficient for the PV separation of phenol from dilute aqueous solutions relative to the separation of methanol. This was due to the fact that phenol has a higher solubility parameter than methanol in silicone membranes. To study the effect of a third component on membrane performance, PV experiments were also carried out with water–phenol–methanol mixtures. The results for total permeation flux and the phenol separation factor for PDMS membranes in contact with water–phenol–methanol ternary mixtures are similar to those in contact with water–phenol binary mixtures. The phenol separation factor of the membrane in contact with the ternary mixture was slightly lower than that in contact with the binary mixture. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献
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Marta Osorio‐Galindo Alicia Iborra‐Clar Isabel Alcaina‐Miranda Amparo Ribes‐Greus 《应用聚合物科学杂志》2001,81(3):546-556
Hydrophobic composite membranes with a crosslinked poly(dimethylsiloxane)‐poly(methyl hydrogen siloxane) selective layer were prepared by using a new laboratory made catalyst agent. The pervaporation separation of five organic solvent–water mixtures was carried out with these composite membranes, together with swelling experiments in the same feed mixtures. The volatile organic compounds employed were ethanol, methanol, 1‐butanol, acetone, and ethyl acetate. The pervaporation and swelling experiments revealed that both the 1‐butanol and the ethyl acetate solutions showed the highest affinity for the composite membrane. When these components were employed as feed solutions, the membranes showed both high selectivity and high permeation. Mechanical–dynamical experiments of swollen and nonswollen composite membranes were also performed. The relaxation spectra were analyzed in terms of the interaction of the components of the different mixtures with the composite membrane, and the free volume corresponding to the each sample was obtained. Once the membranes had reached an equilibrium swelling, a decrease in the free volume was observed. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 546–556, 2001 相似文献
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藻朊酸钠渗透汽化膜分离有机液/水混合物 总被引:1,自引:0,他引:1
研究了藻朊酸钠均质膜及藻朊酸钠/酸丙烯腈复合膜的渗透汽化特性。发现它们对甲醇、乙醇、异丙醇、丙酮、四氢呋喃(THF)、二氧六环、丙三醇等有机溶剂与水的混合望远镜水优选 透过,其渗透通量与选择分离系数都非常高。复合膜与均质膜相比,通量成倍增加,除甲醇/水体系外,对其他体系的分离系数不大,对二氧六环/水体系的分离系数复合膜更高。三种藻朊酸钠样品对乙醇/水,二氧六环/水的透过分离性能有所差异,对此,从膜 相似文献
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近年来膜分离技术被广泛应用于有机物的分离回收。渗透汽化能有效地分离共沸混合物、近沸混合物、异构体和热敏性化合物等有机物。渗透汽化以成本低、条件温和、设备简单、无污染等优点在有机物分离回收领域有着巨大优势,可广泛的应用于工业生产。该文以优先透过有机物为主旨,首先分析了材料对膜结构和特点的影响。其次综述了制备方法和改性方法对膜性能的影响。重点讨论了膜在有机混合物分离回收领域的应用。最后,对目前渗透汽化技术所存在的问题做出了总结,对未来的研究方向和研究思路进行了展望。未来优先透过有机物渗透汽化膜的研究应借助新的计算工具,侧重于材料选择、制备方法和改性方法的改进,如探索具有多功能化学基团和具有明确层次结构的多孔填料的聚合物材料等,使优先透过有机物渗透汽化膜具有更加广阔的应用前景。 相似文献
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The dehydration of aqueous alcohol solutions through asymmetric nylon 4 membranes were investigated using pervaporation processes. The formation of asymmetric pervaporation membranes are discussed in terms of the content of the nonsolvent in the casting solution, polymer concentration, and compositions of the coagulation medium. The effects of the feed composition, feed temperature, and molar volume of the alcohols on the pervaporation performances of the asymmetric membranes are discussed. A separation factor of 4.72 and a permeation rate of 0.78 kg/m2 h for the asymmetric membrane were obtained. Compared to the conventional homogeneous nylon 4 membrane, the asymmetric membrane can effectively overcome the pervaporation performances of the nylon 4 membrane for separation of water–alcohol mixtures. © 1994 John Wiley & Sons, Inc. 相似文献
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G. A. Polotskaya Y. P. Kuznetsov M. Y. Goikhman I. V. Podeshvo T. A. Maricheva V. V. Kudryavtsev 《应用聚合物科学杂志》2003,89(9):2361-2368
Three imide‐containing poly(amic acids) were synthesized and used for homogeneous and composite membrane preparation. The transport properties of composite membranes consisting of an imide‐containing poly(amic acid) top layer on an asymmetric porous poly(phenylene oxide) support were studied in the pervaporation of aqueous solutions of organic liquids (ethanol, isopropanol, acetone, and ethylacetate) and organic/organic mixtures (ethylacetate/ethanol, methanol/cyclohexane). For most of the aqueous/organic mixtures, the composite membranes exhibited dehydration properties. Dilute aqueous solutions of ethylacetate were an exception. In these solutions, the composite membranes exhibited organophilic properties, high permeability, and selectivity with respect to ethylacetate. In the pervaporation of methanol/cyclohexane mixtures, methanol was removed with very high selectivity. To account for specific features of pervaporation on the composite membranes, the sorption and transport properties of homogeneous membranes prepared from polymers comprising the composite membrane [imide‐containing poly(amic acids) and poly(phenylene oxide)] were studied. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2361–2368, 2003 相似文献
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The permeation and pervaporation behaviour of water and several organic solvents through poly[bis(2,2,2-trifluoroethoxy)phosphazene] (PBFP) membrane have been investigated in the temperature range from 42 to 80°C. The steady-state permeation fluxes of the solvents increased in the following order: methanol > ethanol > benzene > water > cyclohexane. An Arrhenius plot of permeation flux of water suddenly changed in its gradient at about 66–70°C, which corresponds closely to the T(1) transition temperature (75°C) of PBFP studied. Interestingly, in the pervaporation of water-methanol mixtures, methanol permeated more rapidly through the membrane than did water; however, the pervaporation of water-ethanol mixtures showed poor permselectivties. In the case of an athermal mixture of methanol and ethanol, the fluxes of methanol and ethanol indicated convex and concave curves, respectively, to the axis of methanol concentration; thus the separation characteristics of this system were slightly better than those of a simple distillation technique. The pervaporation of benzene-cyclohexane mixtures showed excellent permselectivty enrichment in benzene resulting in a separation factor of 12. 相似文献
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Toru Ikegami Tomotake Morita Shunichi Nakayama Hideyuki Negishi Dai Kitamoto Keiji Sakaki Yasunori Oumi Tsuneji Sano Kenji Haraya Hiroshi Yanagishita 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2009,84(8):1172-1177
BACKGROUND: Pervaporation employing ethanol‐permselective silicalite membranes as an alternative to distillation is a promising approach for refining low‐concentration bioethanol solutions. However, to make the separation process practicable, it is extremely important to avoid the problems caused by the adsorption of succinate on the membrane during the separation process. In this work, the pervaporation of an ethanol fermentation broth without succinate was investigated, as well as the influence of several fermentation broth nutrient components. RESULTS: Candida krusei IA‐1 produces an extremely low level of succinate. The decrease in permeate ethanol concentration through a silicone rubber‐coated silicalite membrane during the separation of low‐succinate C. krusei IA‐1 fermentation broth was significantly improved when compared with that obtained using Saccharomyces cerevisiae broth. By treating the fermentation broth with activated carbon, bioethanol was concentrated as efficiently as with binary mixtures of ethanol/water. The total flux was improved upto 56% of that obtained from the separation of binary mixtures, compared with 43% before the addition of activated carbon. Nutrients such as peptone, yeast extract and corn steep liquor had a negative effect on pervaporation, but this response was distinct from that caused by succinate. CONCLUSION: For consistent separation of bioethanol from C. krusei IA‐1 fermentation broth by pervaporation, it is useful to treat the low nutrient broth with activated carbon. To further improve pervaporation performance, it will be necessary to suppress the accumulation of glycerol. Copyright © 2009 Society of Chemical Industry 相似文献
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Membranes consisting of ionically crosslinked polyacrylic acid (PAA) and Nylon 6 were prepared and tested for the pervaporation separation of acetic acid-water mixtures. The polyacrylic acid (PAA) membranes were crosslinked in aluminum nitrate aqueous solution while the polyacrylic acid (PAA)-Nylon 6 blends were cast from homogeneous PAA-Nylon 6 mixtures to appropriate thicknesses and then crosslinked in aqueous aluminum nitrate solutions. Optimum pervaporation results were obtained from blends of Nylon 6 and PAA in the weight ratio of 60–75 wt% Nylon 6 and 25–40 wt% PAA which have separation factors (water/acetic acid) of over 60 and flux rates higher than 100 g/m2 h at 15°C for the separation of acetic acid-water mixtures. The flux rates and separation factors could be altered by changing the blend composition of the membrane. The effects of the feed composition on the separation factors were investigated. 相似文献
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The present study investigated the pervaporation performance of novel hydroxypropylated chitosan (HPCS) membranes to separate water from an aqueous alcohol solution. Hydroxypropylated chitosan was prepared from the reaction of chitosan and propylene oxide. The results show that the separation factor decreases and the flux increases with increasing of the substitution degree of the hydroxypropylated chitosan membrane. Crosslinking with glutaraldehyde or treatment with Cu2+ can improve the pervaporation performance of modified chitosan membrane grately. The performance data indicate that the crosslinking hydroxypropylated chitosan membrane treated with Cu2+ is an excellent pervaporation membrane for the separation of alcohol–water mixtures, and one-stage separation is attainable for some alcohol–water mixtures such as an n-propanol–water and an isopropanol–water system, which has a good separation factor of 220 for the n-PrOH/water system and 240 for the i-PrOH/water system using 85 wt % alcohol concentration at 60°C. The flux for both cases is around 0.5 kg m−2 h−1. At the same time, the structure of the chemically modified chitosan membranes and their separation characteristics for aqueous alcohol solutions are also discussed. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 2035–2041, 1998 相似文献
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Anastasia V. Penkova Galina A. Polotskaya Alexander M. Toikka Vitaly V. Kocherbitov 《Drying Technology》2013,31(6):633-641
The influence of a plasticizer in the form of the residual solvent dimethylacetamide on pervaporation and sorption properties of membranes based on poly(phenylene isophtalamide) (PA) was investigated. To analyze the influence of the plasticizer on membrane transport properties, pervaporation of binary water–ethyl acetate mixtures was studied. The method of sorption calorimetry was used to investigate water sorption properties of the studied membranes and PA powder. Moreover, to characterize the PA membranes, contact angle measurements and thermogravimetric analysis (TGA) were applied. It is shown that the presence of a residual organic solvent significantly changes the sorption and transport characteristics of the membranes. The residual organic solvent increases the amount of water absorbed by the polymer membrane. In pervaporation of water/ethyl acetate mixtures, the presence of the residual solvent dimethylacetamide makes the membrane more permeable but less selective for water separation. 相似文献